106, Extend unit test to check parentheses in WHERE clause

Added two more SQL statements to TestSqlParser.testWhereMoreParsing
Add short-cut logic in StringConverter.convert

This avoids unnecessary reflection and SQL query of large CSV file
worldcitiespop.txt (3 million rows) now runs about 10% faster.
106, correctly parse parentheses in WHERE clause

Fix parentheses parsing in where.jj.  Parentheses are now only parsed
in one place and expressions are generalised to allow parentheses
in any Expression or LogicalExpression.

Add Expression.isValid() to check for invalid SQL expressions such as
(A > 5) + 1 that we cannot detect during parsing.

Call Expression.isValid() after parsing SQL statement to check for
invalid query columns, WHERE clause, or HAVING clause.

Add more WHERE clause expression tests in TestSqlParser.testWhereMoreParsing
Remove unused QueryEnvEntry constructor
Remove HashMap size optimiziation
Merge branch 'master' of ssh://git.code.sf.net/p/csvjdbc/code

Conflicts:
	src/main/javacc/org/relique/jdbc/csv/where.jj
	src/test/java/org/relique/jdbc/csv/TestSqlParser.java
added failOnError false for javadoc plugin
fixed javadoc doclint problems